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NASA's James Webb Space Telescope reaches its final cosmic destination

The telescope traveled a million miles to its destination. Coming next: the first unfiltered images of the universe.

Monisha Ravisetti Former Science Writer
Monisha Ravisetti was a science writer at CNET. She covered climate change, space rockets, mathematical puzzles, dinosaur bones, black holes, supernovas, and sometimes, the drama of philosophical thought experiments. Previously, she was a science reporter with a startup publication called The Academic Times, and before that, was an immunology researcher at Weill Cornell Medical Center in New York. She graduated from New York University in 2018 with a B.A. in philosophy, physics and chemistry. When she's not at her desk, she's trying (and failing) to raise her online chess rating. Her favorite movies are Dunkirk and Marcel the Shell with Shoes On.
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Monisha Ravisetti
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Artist's conception of the James Webb Space Telescope

An artist's conception of the James Webb Space Telescope.

 NASA GSFC/CIL/Adriana Manrique Gutierrez

Born from the visionary dreams of an ambitious crew of scientists, NASA's $10 billion James Webb Space Telescope blasted off on Dec. 25, ready to gaze deep into the cosmos and capture images of the universe as it was when time began. Cheers echoed across the globe as we witnessed the inauguration of astronomy's next great chapter. 

But Webb still had many miles to go. As it unfurled its origami-like folds in space's cold and dark void, the explorer headed toward its cosmic work desk at the second Lagrange point, or L2, where the gravity of the sun and the Earth balance out to keep the satellite in a steady spot.

On Monday, just after 11 a.m. PT/2 p.m. ET, Webb reached its final destination. NASA engineers powered Webb's thrusters for nearly five minutes to perfect the probe's positioning. Beyond applause, the milestone was greeted with a well-deserved exhale.

"Webb, welcome home!" NASA Administrator Bill Nelson said in a statement. "Congratulations to the team for all of their hard work ensuring Webb's safe arrival at L2 today. We're one step closer to uncovering the mysteries of the universe. And I can't wait to see Webb's first new views of the universe this summer!"

Engineering teams celebrate at the Space Telescope Science Institute in Baltimore as the second primary mirror wing of NASA's James Webb Space Telescope unfolds

Engineering teams celebrate at the Space Telescope Science Institute in Baltimore as the second primary mirror wing of NASA's James Webb Space Telescope unfolds, before beginning the process of latching the wing into place on Jan. 8.

 NASA/Bill Ingalls

Webb's galactic address

Now at the second Lagrange point, our new lens on the universe sits 1 million miles away from Earth, well past the moon's orbit, always on the side of our planet not facing the sun. 

Illustration showing Webb's distance from the Earth

Webb will orbit the sun 1.5 million kilometers (1 million miles) away from the Earth at what is called the second Lagrange point or L2. Note: This graphic is not to scale.

 NASA

At this point of gravitational balance, Webb can limit its fuel use and has a terrific view of the cosmos, and its sunshield can protect it from the heat of the sun, the Earth and the moon to sustain the freezing temperatures the telescope needs. The scope must live in a state of constant chilliness because its ability to unlock never-before-seen regions of space lies in its infrared imaging processors. 

These fascinating pieces of machinery work by detecting precise heat signals way out in the cosmos, so heat from its cosmic neighbors – and even from Webb itself – acts like noise in the data. You can read more about the science behind infrared here.

"If you imagine looking at a telescope at night with your own eyes, and someone shines a floodlight in your eyes, you can't see very well," said Alison Nordt, the space science and instrumentation director at aerospace giant Lockheed Martin and part of the Webb team. 

"So if you have a telescope that's dedicated to infrared and you have it at room temperature, then it gets flooded by its own light, which is its own heat."

Now that NASA has locked Webb into place at L2's orbit, it's waiting for the probe to fully cool down, which will take several weeks. Next, as Webb is pulled along its trajectory, the team says it'll focus on ensuring every aspect of the groundbreaking space explorer – such as its 18 mirror segments and infrared imagers – are aligned and ready for action.

In a few months, we'll be receiving our first unfiltered picture of the universe.